Interactions between all the major joint tissues, including the articular cartilage, meniscus, and trabecular bone have been implicated in osteoarthritis (OA). Magnetic resonance (MR) images have been used to quantify the cartilage morphology, volume and thickness, relaxation times T2 and T1?. During the prior funding period, the relationship between cartilage T2 and T1? (mean and spatial heterogeneity), radiographic Kellgren-Lawrence (KL) score, the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), changes in cartilage volume, thickness, trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), fat/water ratios in bone marrow edema like lesions (BMEL) was established. Meniscus and cartilage have similar biochemical constituents, load-dissipating function, and undergo repetitive loading, thus, T2 and T1? methods may also be extended to studying meniscus. Differences in loaded and unloaded T2 and T1? of cartilage and meniscus may reflect biochemical composition and levels of degeneration may potentially be a metric for predicting the progression of OA. This renewal will add to the field of research by extending the quantitative approach of the original proposal to the meniscus, an important tissue in OA, acquire additional years of follow-up for cartilage and bone measures, and examine changes in the soft tissues with loading, where loading at 50% body weight will be accomplished using a device built in-house. Specific Aim 1: To quantify both cross-sectionally and longitudinally (annual over 3 years), differences in regional variations and spatial heterogeneity of T2 and T1? maps of the meniscus in controls and subjects with OA. To establish the correlation of the meniscus metrics with metrics from surrounding and overlying cartilage volume and thickness, cartilage T2 and T1? maps, trabecular bone morphology, morphological grades (WORMS), and functional scores (WOMAC). Specific Aim 2: To compare baseline and longitudinal differences in unloaded and loaded cartilage and meniscus T2 and T1? (loaded T2-unloaded T2 =?T2 and similarly ?T1A) in controls and OA subjects, and whether baseline ?T2 and ?T1A predict disease progression. PUBLIC HEALTH RELEVANCE: This study will develop non invasive biomarkers for cartilage and meniscus degeneration in the knee. We will also examine differences in these tissues with loading. This will help individuals who have or are at risk for developing osteoarthritis.